Owners Urged to Check Horses' WNV Vaccine Status

California State Veterinarian Annette Jones, DVM, sais that "vaccination will provide optimal protection against the disease."

Photo: Anne M. Eberhardt/The Horse

As the weather warms up and mosquitoes become more prevalent, California animal health authorities are urging horse owners to consult their veterinarian to ensure their horses' vaccination status is current for maximum protection against West Nile virus (WNV).

Even though the disease peaked in California a number of years ago, it remains a risk. In 2012, WNV infection was confirmed in 22 California horses, eight of which died or were euthanized. The number of detections was the highest since 2008. In addition, WNV infection was confirmed in 479 people in California, also a significant spike over recent years.

“Outbreaks of West Nile virus are still a risk for horses,” said California State Veterinarian Annette Jones, DVM. “Horse owners should contact their veterinarians as soon as possible to make sure their animals’ vaccination status is current. Vaccination will provide optimal protection against the disease.”

Signs of West Nile virus include stumbling, staggering, wobbling, weakness, muscle twitching, and inability to stand. Horses contract the disease from carrier mosquitoes and are not contagious to other horses or people. Over the past 10 years, approximately 40% of horses infected with WNV died or were euthanized.

Ways to minimize the threat of WNV in horses is to control mosquito populations and prevent exposure to them:

Reduce or eliminate sources of stagnant or standing water that can serve as a breeding ground for mosquitoes, including old tires, buckets, wading pools, and other containers;